1. Field of the Invention
The present invention relates to a portable cordless telephone set in radio-communication with a base telephone unit. More particularly, it relates to a portable cordless telephone set for outputting a variety of discrimination sounds by a simple circuit construction.
2. Description of the Related Art
Portable cordless telephone sets are extensively used because they are connected by radio-communication to base telephone units fixed at certain positions and connected to a telephone exchange; namely, the telephones are not subject to distance limitations imposed by conventional telephone cords and thus are very convenient. A typical portable cordless telephone set incorporates a circuit for generating various discrimination sound and for example, a paging sound, an alarm sound, in addition to a speaker and a microphone. These various discrimination sounds are produced by a combination of a change of sound volumes and a change of ON/OFF patterns.
Prior art portable cordless telephone sets suffer from disadvantages of relative bulkiness, higher costs, and higher power consumption. These disadvantages will be described hereinafter in more detail with reference to the drawings.